In general, a sensory signal output apparatus is an apparatus, such as a speaker, a receiver, a buzzer or a vibratory device (including a vibrator and a linear motor), which converts an electrical signal input from a signal source into a mechanical signal to output a sound or a vibration force, and a bone conduction output apparatus is included.
According to a related art, as shown in FIG. 1, in a sensory signal output apparatus, a magnetic circuit including a magnet 4 and a top plate 5 (a yoke and/or a weight may be further included depending on function and design) which reacts to a magnetic flux generated in a gap according to a direction of an alternating signal applied to a coil 6 which is placed in a space (gap) in an outer circumferential direction or an inner circumferential direction of a yoke 3, the magnet 4, and the top plate 5 generates a vibration force while vibrating, wherein the magnet 4 and the top plate 5 are sequentially stacked on and fixed to a top surface of the yoke 3 through welding-, bonding-, or fitting-fixing, and the bone conduction output apparatus has the same configuration as above. In this case, the magnet 4 and the top plate 5 are corresponding to the magnetic circuit and the coil 6 is corresponding to a vibration-causing portion. The sensory signal output apparatus having the above structure is generally accommodated in a housing-type case 1 and a cover 2, and the yoke 3 to which the magnet 4 and the top plate 5 are fixedly mounted, that is, the magnetic circuit, is supported by a separate leaf spring 7 and fixed to the case 1 (e.g., fixed by a rivet 8, welding-fixed, or fixed to the case by injection molding).
However, because most of the conventional sensory signal output apparatuses are formed in a circular shape and have a large size including the area thereof, the sensory signal output apparatus as described above is limited in application to portable Information Technology (IT) devices which are becoming slimmer, and there is a problem of restricting the slimmer trend of the portable IT devices. When the entire size including the area is miniaturized with the trend of slimming portable IT devices, there may be a problem that a vibration output is lowered and characteristics of high output are restricted. An output may be improved by a structure in which the coil 6 and the magnetic circuit are arranged at a distance at the side of each other along a long axis, but in the conventional long-axis sensory signal output apparatus, each of the coil 6 and the magnetic circuit at each side has a frequency deviation, and thus an error occurs in vibration, which causes a vibrating body to be twisted or causes distortion. In addition, since the magnetic circuit includes the yoke 3 to which the magnet 4 and the top plate 5 are fixedly mounted, a ratio of the volume of magnet relative to the volume of the entire apparatus is small and thus the magnetic force is low. Also, the movement of the magnetic circuit is not restrained in the vibration process and may deviate from the range of vibration, so that a problem arises in that the magnetic circuit collides with the case and generates static (noise), and in order to address this problem, a separate buffering means is required.
Meanwhile, as shown in FIG. 2, in a sensory signal output apparatus according to a related art, an elastically rebounding and supporting means, that is, a leaf spring 7, includes an elastic rebound arm 7c formed between and spaced apart from a circular outer frame 7a and a center surface 7b, one end of the elastic rebound arm 7c is connected to the outer frame 7a and the other end is connected to the center surface 7b, wherein the elastic rebound arm 7c extends in an arc (curved) form while the connecting portions are located at mutually displaced positions.
In the leaf spring 7 as described above, the elastic rebound arm 7c is in the arc (curved) form, so that a response speed of vibration is delayed and thus it is difficult to acquire a quick and precise output characteristic. In addition, connecting portions of each end of the elastic rebound arm 7c are distorted when vibrating, and thus there is a problem that the corresponding portions are torn (damaged) by frequent vibration. Moreover, it may be impossible or difficult to apply the sensory signal output apparatus to a narrow frame (a target to which the sensory signal output apparatus is to be fixed), such as Google Glass phones.